The present invention relates as indicated to a deformable base construction, and relates more particularly to a base capable of absorbing impact forces thereby minimizing injury to players.
An important requirement for baseball or softball bases, particularly at the major league or other high levels of play, is that the base must be mounted to prevent lateral shifting in order for the base to remain in its proper position. There are several ways of accomplishing such mounting, including the use of a long spike which engages a strap affixed to the bottom of the base for securing the base when the spike is driven into the ground. Another commonly used base, and one which is used at the major and minor league levels, is formed with a post which extends into a complimentary shaped retaining sleeve embedded in the soil. The connection is non-rotating, with the post and retaining sleeve assembly thus precluding the base from either rotating or shifting laterally. In both of these known bases, substantial lateral impact forces result when a player slides into the side of the base.
The prior art has suggested dealing with these impact forces in several ways. One such way is to provide a base that breaks away from its mounting when impact forces above a certain level are encountered. U.S. Pat. No. 4,398,715, discloses a base in which the top is detachably secured to a ground plate. When force above a certain level is encountered, the detachable upper portion of the base breaks away from the fixed ground plate. The detachable connection is provided by numerous anchoring points all of which must be secured in order to reattach the base to the plate after the base has broken away.
A different approach is disclosed in applicant's prior U.S. Pat. No. 5,000,447. In the patented base construction, rather than providing a break away base, the base is formed with resilient, inwardly deformable ribs which function to absorb the sliding impact forces, with the resiliency of the ribs returning the ribs to their normal position when the impact forces are terminated.
The base disclosed in applicant's prior U.S. Pat. No. 5,290,028 is similarly laterally inwardly deformable upon impact, but additionally provides a connection between the post and the base such that the base can be separated from the post when the lateral impact forces exceed a predetermined level.